Respirator mask having a circular button



FIG. 1 is a perspective view showing the new design for a respirator mask having a circular button;

FIG. 2 is a front view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a right side view thereof, the left side being a mirror image thereof;

FIG. 5 is a top view thereof; and,

FIG. 6 is a bottom view thereof.

The broken lines in the drawings illustrate portions of the respirator mask having a circular button which form no part of the claimed design. 

CLAIM The ornamental design for a respirator mask having a circular button, as shown and described. 